Camshaft and Crankshaft Sensors?

The dealership couldn't get the car to exhibit the problem with Co-Pilot hooked up so they sent me home with it installed for driving over the weekend. I noticed they put 99 miles on the vehicle, so I would say they definitely tried and I obviously got more than 1 hour of work performed. They told me that Co-Pilot would only record two episodes so there was no need to try to get more than two events.

This morning, from a cold start, about 5-6 minutes after starting and just about at the fully warmed up point, the engine started to stumble and stutter. I was ready with the button on the Co-Pilot and as I approached a stop sign the vehicle died. I pushed the button. After the Co-Pilot cycled through it's procedure and the lights were reset, I restarted the car.

One thing--when the car died the cruise control light lit up. This has happened before, and hopefully it is another clue.

With the button at the ready, and while traveling about 35-40 mph, the engine started to stutter again, the tach going down-up-down-up. After a nice episode of tach dancing I pushed the button again.

Once the vehicle was completely warmed up and had been shut off and restarted (I stopped at a couple of places while out driving) it would no longer show any problems with drivability.

I got some good data points.

Just heard from the dealership. They read the codes off the Co-Pilot and they are getting alternating false signals from the camshaft AND crankshaft sensors. This leads them to believe it is either the cam sensor, the crank sensor, the wiring from the sensors, or the computer control box. They said they tested the wiring and found it to be good and since I've had two sets of cam and crank sensors installed, they suspect the computer control box.

They said I could continue to do diagnostic work at $107 an hour--for example have a guy drive the car and another guy riding along with a scan tool attached until the problem occurred, in which case they would probably get the same error codes as the Co-Pilot and reach the same conclusions.

They asked a couple of technicians for opinions and it was unanimous--computer control box. I asked about them calling and consulting with Chrysler Corporation and they said they are supposed to exhaust every possible cure before calling them and if the computer box didn't fix it they would call them.

A remanufactured Chrysler unit is $590 plus the hour worth of diagnostic work brings it to a little over $700.

I gave them the go-ahead to replace the box.

If they are seeing problems with the cam and crank at the same time, I would suspect a PCM or a wiring problem. The cam and crank get the 8 volt supply from the same pin (#44 orange wire at the C2 connector) I have seen this many times before, but normally by hitting the PCM with a small hammer you can get the vehicle to shut off. It could also be that 1 wire that comes from the PCM to the cam and crank. They could have checked that wire by putting a load on it and did a wiggle test or simply hard wire a new wire into the circuit. My guess would be the PCM is at fault if they indeed saw both cam and crank signal go out. Just a thought

Glenn

They suspect a loose connection inside the PCM. I brought up the hammer test but they didn't seem too open to the suggestion, saying that they could continue to rack up diagnostic charges and still reach the same conclusion--bad PCM.

They said they tested the wiring by putting current through it so I'm guessing they did exactly as you are suggesting.

Thanks, Glenn, you've been most helpful.

Yup that's what they did!!! more then likely that will fix your problem with the PCM

Good luck on it. That was a tough and expensive call. Let us know how it goes. Just for information. The pcm is under federal emmisions warranty for 8 years or 80K and calf may be more. In case of tough cam or crank sensor codes I always like to check the sensors with a lab scope. The lab scope is about the only true way to test the sensors. Did they give you the code no they got?

The total came to "only" $678.

The acid test is tomorrow morning from a cold start. If I can get through the first 5-7 miles it should be OK.

I'm over the 8 years, but under the 80K.

How do you test them?

No. But here's the write-up on my receipt:

"Checked Co-Pilot data. In the first recording the crank sensor signal was lost. In the second recording the cam sensor signal was lost. Inspected wiring for cam and crank position sensors, resistance tested,

8 V circuit, ground, cam signal and crank signal wires from PCM. Each circuit could draw power well. Light bulb lit up bright on each circuit. That left PCM as only possible cause for concern."

Thanks for your input also. It's been quite the learning experience.

Its to bad such an easy thing could be dragged out so long

Glenn

You are welcome and 10-4 it has gave you fit.

That is a bummer on being over on time on pcm warranty.

A lab scope is on the order of a ign scope. But it is for checking electrical signals like all sensors signals. When hooked up to the sensor it will graft out the true sensor signal and show any signal glitzes/break down/up or acting up. It gets down to the nitty gritty when testing sensors.

With a dual lab scope you could watch the crank and cam signal at the same time and see if there is any signal lose or break up. But it needs to be tested at the time it acts up.

We hope the PCM fixes it. But If it gives you any more problems I would ask for a lab scope test. Good Luck MT

OK, three days of driving, about 90 miles, including three cold starts, and no problems. I think we've got it fixed.